The present invention relates to a metal laminate cylinder head gasket for an open deck type engine.
A light weight automobile engine has been developed to provide high power. In order to satisfy this demand, a cylinder block may be made of an aluminum alloy, and in some cases, formed by die casting to become an open deck type, so that the molded cylinder block can be easily removed from the die.
One example of the open deck type cylinder block 10 is shown in FIG. 1. The cylinder block 10 is formed integrally as one unit, and includes cylinder walls 12 for defining cylinder bores 11 therein and an outer frame or main body 13. The cylinder walls 12 are connected together at connecting portions 14. The cylinder walls 12 are also connected to the outer frame 13 at bottom portions 14' thereof, and form therebetween a space 15. Cooling liquid or water circulates through the space 15 for cooling the cylinder bores 11.
The outer frame 13 includes bolt holes 16 for connecting with a cylinder head (not shown). Also, an oil hole 17 is formed in the outer frame 13 for circulating oil. As shown in FIG. 2, cylinder liners 18 may be installed inside the cylinder walls 12.
In order to seal the open deck type engine, a gasket 20 is used. The gasket 20 is formed of an upper plate 21, a middle plate 22, and a lower plate 23. The upper plate 21 includes a water hole 21a, a curved portion 21b for defining the cylinder bore 11, and a flange 21c. The middle plate 22 includes a water hole 22a, and beads 22b, 22c extending along the space 15 for sealing at side portions of the space 15. The lower plate 23 includes a water hole 23a, and a bead 23b extending around the cylinder bore 11 for sealing therearound.
In the conventional gasket 20, coatings may be formed on the entire outer surfaces of the gasket for sealing and filling out small scratches formed on the cylinder block and the cylinder head. Further, soft seal coatings may be formed on the entire surfaces of the middle plate to prevent liquid from flowing between the plates.
However, in case the soft seal coating is formed on the entire outer surfaces of the middle plate, a part of the coating formed on the beads may wear or be broken, because the cylinder wall 12 vibrates severely.
In U.S. Pat. No. 4,968,045, a plate for forming a gasket is made so that a portion of the plate for contacting cooling liquid does not have a seal coating. As a result, the seal coating does not enter into the cooling liquid, and consequently, clogging of a water circulating system of an engine is prevented.
In the open deck type engine, the cylinder walls vibrate severely, so that if the coating is formed on the cylinder PG,4 wall, the coating may wear or break. None of the prior art gaskets solves this problem.
Accordingly, one object of the present invention is to provide a metal laminate gasket for an open deck type engine, wherein an area around a water hole is securely sealed.
Another object of the invention is to provide a metal laminate gasket as stated above, which can be easily and economically manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.